The responses of pulpal tissue to restorative materials in class V cavity preparations in primate teeth do not correlate well with either in vitro tests or implantation tests. It is thought that a major reason for this is the lack of attention which has been paid to the filtration and adsorption/absorption properties of the intervening dentin. The objectives of this present application are (1) to study the filtration and adsorption/absorption characteristics of human molar dentin, (2) to attempt to simulate these characteristics with a hydroxyapatite/ type I collagen compact column, (3) to study the response of intact human odontoblasts in an "in-vitro pulp chamber" to various concentrations of partially reacted polymerization products of posterior composities and bonding systems as well as to bacteria and bacterial products, and (4) to attempt to simulate these odontoblastic responses by a standardized cell culture in the same chamber. It is believed that this methodology should provide the basis for a relatively inexpensive and accurate predictor test for assaying experimental dental restorative materials prior to final "usage" tests in primates. Finally, if the hypothesis is true that bacterial metabolites are a major factor in causing pulp reactions in usage tests, then the in-vitro pulp chamber will serve as the most effective way of determining how the cavity preparations and materials should be manipulated to eliminate bacterial infection.